Kornack D R
Center for Aging and Developmental Biology, Department of Neurobiology and Anatomy, University of Rochester Medical Center, Rochester, NY 14642, USA.
Brain Behav Evol. 2000 Jun;55(6):336-44. doi: 10.1159/000006668.
The mammalian cerebral cortex varies enormously in absolute and relative size across species. These size differences reflect phyletic differences in the number and organization of cortical neurons, which in turn imply evolutionary changes in the developmental program that generates these neurons. Whereas patterns of symmetric and asymmetric modes of progenitor cell division during cortical neurogenesis are widely conserved among species, other proliferation parameters, including the timing and number of cell divisions, vary considerably. This variation contributes to the development of cortical size differences in mammals in general, and the expansion of neocortex in anthropoid primates (monkeys, apes, and humans) in particular. The disproportionate enlargement of anthropoid neocortex might also arise from regional 'border-shifting' within the embryonic telencephalon, causing expansion of the neurogenic region allocated for producing neocortex and concomitant diminution of neighboring olfactory regions. Neurogenesis also shows substantial phyletic differences in adult hippocampus, an archicortical structure. Therefore, variation in neurogenesis across species is not only a feature of early development, but is also a trait of adult cortical diversity.
哺乳动物的大脑皮层在绝对大小和相对大小上因物种而异。这些大小差异反映了皮层神经元数量和组织的系统发育差异，这反过来又意味着产生这些神经元的发育程序发生了进化变化。虽然在皮层神经发生过程中祖细胞对称和不对称分裂模式在物种间广泛保守，但其他增殖参数，包括细胞分裂的时间和数量，差异很大。这种变化总体上促成了哺乳动物皮层大小差异的发展，尤其是类人猿灵长类动物（猴子、猿和人类）新皮层的扩张。类人猿新皮层的不成比例扩大也可能源于胚胎端脑内的区域“边界转移”，导致分配用于产生新皮层的神经源性区域扩张，同时相邻嗅觉区域缩小。神经发生在成年海马体（一种古皮层结构）中也表现出显著的系统发育差异。因此，跨物种神经发生的变化不仅是早期发育的一个特征，也是成年皮层多样性的一个特征。
